Known compute-intensive network applications demand increased bandwidth. With the deployment of multi-media workstations, the use of image processing in the healthcare and banking industries, electronic publishing, and CAD/CAE applications in the engineering environment, an internetworking product which can support performance requirements across practically any geographic distance is required.
In general, a network includes a collection of autonomous machines which are interconnected (e.g., via wires, optical fibers, satellites, etc.) in order to run user (i.e., application) programs. A computer network is a network which typically includes at least one autonomous computer. The term network as used herein generally should be taken to mean computer network. Internetworking generally means the connection of two or more computer networks to allow an exchange of information between the networks. The information exchanged between ("inter") the various networks and among ("intra") the individual networks typically is contained in discrete packets which can be arranged in a variety of formats.
Bridges and routers generally are internetworking devices which can be used to interconnect or extend packet-based local area networks (LANs) or subnetworks. Both bridges and routers can make forwarding or routing decisions based on information in the LAN packet headers. A bridge differs fundamentally from a router. A bridge typically relays Media Access Control (MAC) layer (or data link layer which is layer two in the OSI model) frames and decisions are made based on information in the frame header. A router relays network layer (layer three in the OSI model) datagrams an decisions are based on information in the network layer header. This fundamental difference affects the way each type of device operates, and consequently, the applications to which it is best suited.
Bridges and routers currently employed for internetworking typically use shared-bus architectures in which bandwidth is shared between networks on a statistical first come, first served basis.
Because network downtime usually equates to lost productivity, lost business, and user dissatisfaction, many companies desire a reliable, robust internetworking device that provides high system and network availability as well as the security of non-stop networking for many, if not all, network applications.
To be most useful, an internetworking device should maximize reliability, availability, and serviceability. Also, the device should provide organizations with the flexibility and the performance capability required to accommodate organizational growth and technological evolution.